The present invention relates to the technique for solder-connecting a head provided on a slider of a magnetic disk drive, a magneto-optical disk drive or the like and a lead wire connected to a circuit base plate, and more specifically, to the technique for enhancing the positive properties of connection between a slider pad and a lead wire using a solder ball.
In the magnetic disk drive, a head for converting a magnetic signal to an electric signal carries out writing or reading of data with respect to the magnetic disk. A head and a slider constitute a head/slider, and a supporting structure called a suspension assembly supports the head/slider. The head/slider flies, in reading or writing data, above the magnetic disk which rotates at high speed while performing track following operation called pitch and roll movement or gimbals movement.
A semiconductor chip for carrying out control and data transfer of the magnetic disk drive is mounted on the circuit base plate, and it is necessary to electrically connect the head and the circuit base plate of the magnetic disk drive by means of a lead wire. Recently, as recording density enhances, demand of the head with respect to the control characteristics becomes severe, influence of weight, arrangement and the like of the lead wire on positional control of the head cannot be ignored. As a result, there is a tendency that a wiring integrated type flexure assembly is employed in which a wiring is adhered to or a wiring pattern is formed on the flexure to reduce unbalance given by the wiring to the gimbals characteristics of flexure. In the wiring integral type flexure assembly, the sliding pad connected to the head need be connected electrically to the end of the lead wire. As one connecting method, there is a supersonic adhesion method as shown in Japanese Patent Laid-Open No. Hei 11-96710. In this method, the end of the lead wire is placed on the slider pad to provide connection while giving vibrations to a gold ball by means of a bonding tool. Recently, the magnetic disk drive is further miniaturized, the slider is also miniaturized, and the gimbals movement is made finer, because of which it becomes necessary to reduce the stress as much as possible on the slider or the lead wire when the lead wire is connected. Further, in the supersonic adhesion method, there is a fear that static electricity generated in the course of adhesion is discharged to break the slider or the head, and there is pointed out limitation as the adhesion method for further miniaturized head/slider.
As another method for connecting the head/slider and the lead wire, there exists a solder ball adhesion method capable of connecting with respect to a connection portion in non-contact. Japanese Patent Laid-Open No. 2002-251705 discloses the technique regarding the slider ball adhesion method. FIGS. 4 and 5 of that patent reference show a method in which the bonding pad and lead pad provided on the slider are arranged at right angles, the spherical solder ball is temporarily fixed so as to come in contact with both the pads, and afterward, the solder allows re-flow by a laser beam to provide solder connection. Further, Patent Japanese Patent Laid-Open No. 2003-123217 likewise relates to the solder ball connection, and FIGS. 4 and 5 and the description of that patent reference clearly describes that an angle between the head pad and the lead pad is 90 degrees.
In U.S. Pat. No. 5,896,247, the prior art with respect to the invention of Patent Document 4 is described referring to FIG. 5 thereof. In the description of FIG. 5 in that patent document, there is described that prior to mounting the slider, the flexure tang mounting the slider and the support layer are at the same level. Further, there is described that it is necessary to extend the dielectric layer toward the slider from the copper trace in order to eliminate possible short-circuiting trouble, and as a result, the slider is mounted on the flexure tang, and during the copper trace and the transducer pad are connected by solder ball or gold ball, the dielectric layer has to be pressed down by the thickness of the dielectric layer under the slider.